fn main() {
    let s ="Hello";
    println!("{}", s);
    {
        let s = "world";
        println!("{}", s);
    }
    println!("{}", s);
    let mut s2 = String::from("Hi");
    s2.push_str(" World");
    println!("{}", s2);
    let s3 = s2.clone();
    println!("{}", s3);
    println!("{}", s2);

}
